Methods to produce sulfate-free saline water and gypsum

Abstract

Methods are disclosed for the selective separation of sulfate from a saline stream such as seawater to produce nearly sulfate-free saline stream for oil-fields water injection operations. The separated sulfate in the form of gypsum from the treated saline stream can be used in different applications.

1. A method for separating sulfate from saline water to produce nearly sulfate-free saline stream and gypsum, said method comprising the steps of:
 (a) removing sulfate from said saline water by
 (i) concentrating said saline water by membrane system to produce an intermediate concentrate comprising at least gypsum, said gypsum having an increased concentration in said intermediate concentrate; 
 (ii) pressurizing said intermediate concentrate into a precipitator at pressure between about 400 psi and about 1,200 psi through at least one nozzle to produce a jet stream of said intermediate concentrate; 
 (iii) pressurizing amine solvent or amine solvent with modifier into said precipitator at pressure between about 400 psi and about the critical pressure of said amine solvent or said amine solvent with modifier through at least one nozzle to form micron-size precipitates comprising said gypsum from said intermediate concentrate; 
 (iv) removing said micron-size precipitates from said intermediate concentrate by filter to produce gypsum slurry; 
 (v) removing at least most of said amine solvent or said amine solvent with modifier from said intermediate concentrate by stripper to produce said nearly sulfate-free saline stream; 
 
 (b) injecting said nearly sulfate-free saline stream into subterranean formation for hydrocarbons recovery; 
 (c) producing gypsum boards or gypsum materials from said gypsum slurry by
 (i) separating said gypsum slurry into moist solid gypsum and liquor stream by filter; 
 (ii) removing at least most of remaining said amine solvent or said amine solvent with modifier from said liquor stream by stripper; 
 (iii) recycling said liquor stream to said intermediate concentrate; 
 (iv) molding said moist solid gypsum to produce said gypsum boards or said gypsum materials; 
 (v) allowing said gypsum boards or said gypsum materials to dry; or 
 
 (d) producing potassium sulfate from said gypsum slurry by
 (i) adding potassium chloride to said gypsum slurry to produce intermediate liquor stream; 
 (ii) adding said amine solvent or said amine solvent with modifier to said intermediate liquor stream to form precipitates comprising said potassium sulfate; 
 (iii) removing said precipitates from said intermediate liquor stream by filter; 
 (iv) removing at least most of said amine solvent or said amine solvent with modifier by stripper; and 
 (v) recycling said intermediate liquor stream comprising at least dissolved calcium chloride to said intermediate concentrate. 
 
 
     
     
       2. The method of  claim 1  wherein said saline water is seawater, natural brine water, oil-gas fields produced water, coal-bed produced water, mining operations produced water, flue gas desulphurization produced water, or a combination thereof. 
     
     
       3. The method of  claim 1  wherein said membrane system is reverse osmosis, nanofiltration, membrane distillation, membrane osmotic distillation, or a combination thereof. 
     
     
       4. The method of  claim 1  wherein said nozzle is coaxial nozzle, spray nozzle, vibrating nozzle, premixed nozzle, or a combination thereof. 
     
     
       5. The method of  claim 1  wherein said amine solvent is selected from the group consisting of isopropylamine, propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine, methylamine, dimethylamine, or a combination thereof. 
     
     
       6. The method of  claim 1  wherein said modifier is nitrogen, nitrous oxide, or a combination thereof. 
     
     
       7. The method of  claim 1  wherein said modifier is mixed with said amine solvent in an amount to reduce the critical temperature of said amine solvent. 
     
     
       8. The method of  claim 1  wherein said modifier is mixed with said amine solvent in said amount not to affect polarity, basicity, miscibility, and precipitating ability of said amine solvent in said saline water. 
     
     
       9. The method of  claim 6  wherein said modifier is liquid or gas. 
     
     
       10. The method of  claim 1  wherein said filter is hydrocyclone, microfiltration, vacuum filter, press filter, centrifugal filter, electrostatic filter, or a combination thereof. 
     
     
       11. The method of  claim 1  wherein said stripper is flash tank, distillation column, vacuum distillation, vacuum membrane distillation, pervaporation, or a combination thereof. 
     
     
       12. A method for separating sulfate from saline water to produce nearly sulfate-free saline stream and gypsum, said method comprising the steps of:
 (a) concentrating sulfate in said saline water by
 (i) pressurizing said saline water into a precipitator at pressure between about 400 psi and about 1,200 psi through at least one nozzle to produce a jet stream of said saline water; 
 (ii) pressurizing amine solvent or amine solvent with modifier into said precipitator at pressure between about 400 psi and about the critical pressure of said amine solvent or said amine solvent with modifier through at least one nozzle to form at least some micron-size precipitates comprising said gypsum from said saline water; 
 (iii) classifying said micron-size precipitates into fine micron-size precipitates and large micron-size precipitates by filter; 
 (iv) recycling said fine micron-size precipitates into a pre-precipitator to mix with said saline water to produce intermediate saline water; said gypsum having an increased concentration in said intermediate saline water; 
 
 (b) removing sulfate from said intermediate saline water by
 (i) pressurizing said intermediate saline water into said precipitator at said pressure between about 400 psi and about 1,200 psi through at least one said nozzle to produce said jet stream of said intermediate saline water; 
 (ii) pressurizing said amine solvent or said amine solvent with modifier into said precipitator at said pressure between about 400 psi and about said critical pressure of said amine solvent or said amine solvent with modifier through at least one said nozzle to form large micron-size precipitates comprising said gypsum from said intermediate saline water; 
 (iii) removing said large micron-size precipitates from said intermediate saline water by filter to produce gypsum slurry; 
 (iv) removing at least most of said amine solvent or said amine solvent with modifier from said intermediate saline water by stripper to produce said nearly sulfate-free saline stream; 
 
 (c) injecting said nearly sulfate-free saline stream into subterranean formation for hydrocarbons recovery; 
 (d) producing gypsum boards or gypsum materials from said gypsum slurry by
 (i) separating said gypsum slurry into moist solid gypsum and liquor stream by filter; 
 (ii) removing at least most of remaining said amine solvent or said amine solvent with modifier from said liquor stream by stripper; 
 (iii) recycling said liquor stream to said saline water; 
 (iv) molding said moist solid gypsum to produce said gypsum boards or said gypsum materials; 
 (v) allowing said gypsum boards or said gypsum materials to dry; or 
 
 (e) producing potassium sulfate from said gypsum slurry by
 (i) adding potassium chloride to said gypsum slurry to produce intermediate liquor stream; 
 (ii) adding said amine solvent or said amine solvent with modifier to said intermediate liquor stream to form precipitates comprising said potassium sulfate; 
 (iii) removing said precipitates from said intermediate liquor stream by filter; 
 (iv) removing at least most of said amine solvent or said amine solvent with modifier by stripper; and 
 (v) recycling said intermediate liquor stream comprising at least dissolved calcium chloride to said saline water. 
 
 
     
     
       13. The method of  claim 12  wherein said saline water is seawater, natural brine water, oil-gas fields produced water, coal-bed produced water, mining operations produced water, flue gas desulphurization produced water, or a combination thereof. 
     
     
       14. The method of  claim 12  wherein said nozzle is coaxial nozzle, spray nozzle, vibrating nozzle, premixed nozzle, or a combination thereof. 
     
     
       15. The method of  claim 12  wherein said amine solvent is selected from the group consisting of isopropylamine, propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine, methylamine, dimethylamine, or a combination thereof. 
     
     
       16. The method of  claim 12  wherein said modifier is nitrogen, nitrous oxide, or a combination thereof. 
     
     
       17. The method of  claim 12  wherein said modifier is mixed with said amine solvent in an amount to reduce the critical temperature of said amine solvent. 
     
     
       18. The method of  claim 12  wherein said modifier is mixed with said amine solvent in said amount not to affect polarity, basicity, miscibility, and precipitating ability of said amine solvent in said saline water. 
     
     
       19. The method of  claim 16  wherein said modifier is liquid or gas. 
     
     
       20. The method of  claim 12  wherein said filter is hydrocyclone, microfiltration, vacuum filter, press filter, centrifugal filter, electrostatic filter, or a combination thereof. 
     
     
       21. The method of  claim 12  wherein said stripper is flash tank, distillation column, vacuum distillation, vacuum membrane distillation, pervaporation, or a combination thereof. 
     
     
       22. A method for separating sulfate from saline water to produce nearly sulfate-free saline stream and gypsum, said method comprising the steps of:
 (a) removing sulfate from said saline water by
 (i) pressurizing said saline water into a precipitator at pressure between about 400 psi and about 1,200 psi through at least one nozzle to produce a jet stream from said saline water; 
 (ii) pressurizing amine solvent or amine solvent with modifier into said precipitator at pressure between about 400 psi and about the critical pressure of said amine solvent or said amine solvent with modifier through at least one nozzle to form at least some micron-size precipitates comprising said gypsum from said saline water; 
 (iii) classifying said micron-size precipitates into fine micron-size precipitates and large micron-size precipitates by filter; 
 (iv) recycling said fine micron-size precipitates into said precipitator at pressure between about 400 psi and about 1,200 psi through at least one nozzle to produce large micron-size precipitates comprising said gypsum from said saline water; 
 (v) removing said large micron-size precipitates from said saline water by filter to produce gypsum slurry; 
 (vi) removing at least most of said amine solvent or said amine solvent with modifier from said saline water by stripper to produce said nearly sulfate-free saline stream; 
 
 (b) injecting said nearly sulfate-free saline stream into subterranean formation for hydrocarbons recovery; 
 (c) producing gypsum boards or gypsum materials from said gypsum slurry by
 (i) separating said gypsum slurry into moist solid gypsum and liquor stream by filter; 
 (ii) removing at least most of remaining said amine solvent or said amine solvent with modifier from said liquor stream by stripper; 
 (iii) recycling said liquor stream to said saline water; 
 (iv) molding said moist solid gypsum to produce said gypsum boards or said gypsum materials; 
 (v) allowing said gypsum boards or said gypsum materials to dry; or 
 
 (d) producing potassium sulfate from said gypsum slurry by
 (i) adding potassium chloride to said gypsum slurry to produce intermediate liquor stream; 
 (ii) adding said amine solvent or said amine solvent with modifier to said intermediate liquor stream to form precipitates comprising said potassium sulfate; 
 (iii) removing said precipitates from said intermediate liquor stream by filter; 
 (iv) removing at least most of said amine solvent or said amine solvent with modifier by stripper; and 
 (v) recycling said intermediate liquor stream comprising at least dissolved calcium chloride to said saline water. 
 
 
     
     
       23. The method of  claim 22  wherein said saline water is seawater, natural brine water, oil-gas fields produced water, coal-bed produced water, mining operations produced water, flue gas desulphurization produced water, or a combination thereof. 
     
     
       24. The method of  claim 22  wherein said nozzle is coaxial nozzle, spray nozzle, vibrating nozzle, premixed nozzle, or a combination thereof. 
     
     
       25. The method of  claim 22  wherein said amine solvent is selected from the group consisting of isopropylamine, propylamine, dipropylamine, diisopropylamine, ethylamine, diethylamine, methylamine, dimethylamine, or a combination thereof. 
     
     
       26. The method of  claim 22  wherein said modifier is nitrogen, nitrous oxide, or a combination thereof. 
     
     
       27. The method of  claim 22  wherein said modifier is mixed with said amine solvent in an amount to reduce the critical temperature of said amine solvent. 
     
     
       28. The method of  claim 22  wherein said modifier is mixed with said amine solvent in said amount not to affect polarity, basicity, miscibility, and precipitating ability of said amine solvent in said saline water. 
     
     
       29. The method of  claim 26  wherein said modifier is liquid or gas. 
     
     
       30. The method of  claim 22  wherein said filter is hydrocyclone, microfiltration, vacuum filter, press filter, centrifugal filter, electrostatic filter, or a combination thereof. 
     
     
       31. The method of  claim 22  wherein said stripper is flash tank, distillation column, vacuum distillation, vacuum membrane distillation, pervaporation, or a combination thereof.